The present invention relates to a method for controlling the injection in a fuel injection system of an internal combustion engine which can operate selectively with petrol or fuel gas, and an associated injection system.
As is known, the increasingly severe limits imposed by the various legislations against pollution emissions from internal combustion engines have created a new interest on the part of manufacturers for fuel gas engines. Initially, fuel gas engines were provided with a device for metering fuel gas to be mixed with air supplied to the engine in an arrangement similar to that of a normal carburettor of a petrol engine.
With development in technology this arrangement became unacceptable in that it did not lend itself to operating in conjunction with an electronic engine control system, in particular one able to control the fuel metering as a function of the composition of the exhaust gases detected by means of a lambda probe.
Subsequently, engines which could run on fuel gas and which were provided with an injection system were therefore studied.
The increasing use of this type of engine, operating selectively with petrol injection or fuel gas, has required the study and development of ever more efficient injection control methods in terms of the level of pollution and energy efficiency.
The object of the present invention is that of providing an injection control method and an injection system which makes it possible to obtain reduced levels of pollution and high energy efficiency in all operating conditions of the engine.
According to the present invention there is provided a method for controlling a fuel injection system for an internal combustion engine having a plurality of cylinders and selectively operable with petrol injection or fuel gas, the said method including supplying fuel gas to the said cylinders, characterised in that in each engine cycle the fuel gas is supplied selectively to some of the cylinders of the said engine on the basis of the required power.
According to the present invention there is further provided a fuel injection system for an internal combustion engine having a plurality of cylinders and selectively operable with petrol or fuel gas, characterised in that it includes fuel gas supply means selectively operable to supply fuel gas, in each engine cycle, selectively to some of the said cylinders of the said engine on the basis of the required power.